Haha. Well, I found the same thing... When my noise came about, it was after it had boiled over. But I didn't think I lost much coolant. The same trip, I crushed my left radiator. I never thought to check the water level, but never thought low water would be a symptom of that noise. So when I pulled the radiator, I noticed the level was low, about 3/4q ( which is about half-ish empty ). I straightened out the rad, re installed and noticed while doing my leak check, the noise was gone... ? So I took it to a woods race and mx track this weekend... No noise.